The regular use of smokeless tobacco (ST) represents a serious public health problem. Most tobacco treatment programs do not offer specific ST interventions and ST users have little or no access to tobacco treatment programs. Therefore, a need exists to develop cost effective ST interventions that can be disseminated broadly. Our earlier research demonstrated that behavioral self-help interventions using mailed materials plus telephone support produced long-term ST cessation. While most nicotine replacement interventions have been surprisingly ineffective with ST users, the nicotine lozenge has shown promising results. We recently demonstrated that using nicotine lozenges increased all tobacco and ST tobacco abstinence rates at follow-up and a pilot study demonstrated the feasibility of an ST intervention consisting of nicotine lozenges delivered in the context of an assisted self-help intervention. The next step in this line of research is to test the effectiveness and cost-effectiveness of a minimal contact intervention combining nicotine lozenge and assisted self-help that could be disseminated broadly. Objectives: We propose a three-arm RCT that rigorously tests the effectiveness of three ST cessation programs: (a) a condition that combines the use of nicotine Lozenges and Assisted Self-Help phone counseling (LASH) (b) a condition that receives only the Assisted Self-Help (ASH: including phone support), and (c) a minimal contact condition that receives Lozenges and Self-Help materials (LSH). Methods: A multifaceted, data-driven marketing and promotion plan will be used to recruit 1011 ST users. Prospective participants will call a toll-free recruitment line for preliminary screening. Individuals who complete a mailed enrollment packet (informed consent and baseline assessment) will be randomized to one of the three conditions and receive a combination of lozenges via the mail, three telephone support calls from a counselor and self-help materials. The primary outcome measure will be self-reported prolonged abstinence from all tobacco use at 3- and 6-month follow-up. We will biochemically verify abstinence at the 6 month assessment. Measures: Tobacco abstinence outcomes will be evaluated at 3 months and 6 months post-enrollment via mailed surveys and phone calls to non-responders. Secondary analyses will examine baseline participant characteristics, program utilization, and moderators and mediators of tobacco abstinence. An exploratory test of liver enzyme activity on the metabolism of nicotine will be tested as a potential moderator for the efficacy of the nicotine lozenge. We will also assess the incremental cost-per-quit of adding nicotine lozenges to an assisted self-help intervention (or of adding an assisted self-help intervention to a lozenge intervention). Benefits: This project will be the first RCT for ST cessation that tests the incremental effectiveness of using nicotine lozenges along with a behavioral intervention featuring phone counseling and also whether the behavioral intervention adds value to the lozenges. PUBLIC HEALTH RELEVANCE: There is a need for a smokeless tobacco cessation program that is cost effective and has the potential to reach this group of underserved tobacco users. Using a three-arm design, we propose to evaluate the effectiveness and cost-effectiveness of combining a validated behavioral intervention with a promising Nicotine Replacement Therapy-the Lozenge-compared to either intervention alone.